1. Field of the Invention
The present invention relates to a method and device for determining greenhouse gas, in particular methane, emitted by a ruminant, in particular a dairy animal.
2. Description of the Related Art
Greenhouse gases play a part in climate change. Livestock breeding makes a substantial contribution to the emission of greenhouse gases, such as carbon dioxide and in particular methane. The global warming potential of methane is 20 to 25 times greater than that of carbon dioxide. The greatest part of this emission is caused by eructations. An average cow is estimated to emit between 500 and 600 litres of methane per day through belching and exhalation. Methane is produced by ruminants as a by-product of the fermentation of organic mass in the gut. It constitutes a significant loss of energy for the animal, estimated at 2 to 12% of the gross energy intake.
It is desirable to find a simple way to determine, or at least estimate, the emission of greenhouse gas, and in particular methane, in the case of animals.
A method and system for measuring emitted greenhouse gas are known from U.S. Pat. No. 5,265,618. Here, a tube with tracer gas (SF6) is swallowed by the animal, from which tube the tracer gas leaks. Furthermore, a sampling system is fitted to the mouth of the animal, where breath samples are taken via a sampling tube. The emission of the greenhouse gas can be determined by analysing the breath samples, wherein proportions of greenhouse gas and tracer gas in relation to the ambient air are determined.
A disadvantage of the known method and system is that this is very complicated, in that the animal must swallow a tracer gas tube and a gas analysis is then carried out using gas analysis equipment. This makes the known method less suitable for application in the case of entire herds of animals. Furthermore, the global warming potential of the tracer gas (SF6) is again a thousand times greater than that of methane